This invention relates to battery power supplies and, more particularly, to an arrangement for insuring a minimum output voltage from such a supply.
Battery powered remote instruments for data collection and transmission utilized by utility companies are often subjected to harsh environmental conditions. Thus, a piece of equipment such as an electronic pressure recorder mounted on a gas pipeline may be located in a desert region where the daytime temperatures can exceed 120.degree. F. or it may be located in an arctic region where nighttime temperatures can drop below -30.degree. F. No matter where such equipment is installed, the electronic circuitry requires a minimum battery voltage for its operation. Thus, for example, equipment which utilizes a nominal nine volt battery supply requires a minimum of seven volts for proper operation. It is known that as the temperature of a battery decreases, its terminal voltage decreases. Thus, when the ambient temperature reaches -30.degree. F., the terminal voltage of a nominal nine volt battery may drop below seven volts. Unless there is compensation for this effect, the electronic equipment powered by such a battery is rendered ineffective. It is therefore an object of the present invention to provide an arrangement which insures that the output voltage from a battery supply is maintained above a predetermined threshold.